HAIR SHAFT DAMAGE AFTER UV IRRADIATION 155 25hD 2011D UVA 151tD IOlcD 251tD 20110 1511D UVB lOltD Figure 4. Western blot analysis of UV-light-irradiated hair samples with ubiquitin antibodies. Upper panel: after UV A irradiation. Lower panel: after UVB irradiation. parison to the hair shafts after UV A irradiation, there are a few relatively weak positive findings around the 1 0kDa area after UVB irradiation. We think that the positive finding before UV A irradiation may result from the preceding natural weathering processes. There have been several reports on the evaluation of photoaging and photoprotection of hair fibers with microscopy. Braida et al. (9) reported TEM findings on hair shafts after using two kinds of sunlight stimulators. On the other hand, Bousquet et al. ( 10) reported analysis of patterns of cuticles for evaluation of hair photoprotection with confocal microscopy. The former revealed the difference in melanin particles in irradiated hair samples with TEM, and the latter reported morphological findings in hair cuticles with confocal microscopy. In this study, we carried out investigations with four detailed tools having different strong points: SEM findings reveal superficial cuticular changes, con- ventional TEM findings reveal deep cuticular changes, and TEM findings using Lee's fixative reveal intercellular lipid layer changes more precisely. We also performed a protein analysis using ubiquitin antibodies. Ubiquitin-mediated degradations of regu- latory proteins are known to play important roles in numerous processes, including cell-cycle progression, signal transduction, transcriptional regulation, receptor down- regulation, and endocytosis (11). In a recent study, Inoue et al. have suggested that ubiquitin could be an indicator of hair damage. It was reported that the main wavelength of UV light absorbed by keratin was UVB, which could do damage mainly by the cleaving of the protein bonds and protein crosslinking (12). In the hair shaft, UVB is known to penetrate about 5 µm in depth, and the intensity decreases exponentially after that (12). Considering that intact hair cuticles are 6-10 layers, each with a thickness of 0.3-0.5µm, UVB seems mainly to affect the cuticles. This suggests that hair damage by UVB irradiation is mainly confined to the superficial layers of the hair shaft, the cuticle layers. We think our findings are related to the penetration depth of UV light mentioned above. UV A irradiation can penetrate deeply into the cortex, and so biochemical changes, including cuticles and

156 JOURNAL OF COSMETIC SCIENCE cortex together, may appear greater after UV A irradiation. On the other hand, UVB causes severe morphological damage, confined to the hair cuticles because of its restricted depth of penetration. CONCLUSIONS In summary, our morphological study shows relatively more destructive cuticular changes after UVB irradiation than after UV A, while disruptions of the intercellular lipid layer show similar results between UVA and UVB irradiation. However, in labile protein analysis, damaged labile hair proteins are much more observed after UVA irradiation than after UVB irradiation. Because high doses of UV light were irradiated to observe patterns of damage in this report, we'd like to plan to observe chronically photodamaged hair shafts as similar as possible to those in daily life. Based on the principal findings here, we hope it will be useful to study the photoaging of hair and photoprotective methods in hair. Other biochemical methods, including amino acid analysis and lipid analysis, would be helpful to understand the process of UV-light- induced damage to hair. ACKNOWLEDGMENTS This research was supported by Health Fellowship Foundation grants in Korea. REFERENCES (1) "Oxidation of Hair Proteins and the Cell Membrane Complex by Sun and Ultraviolet Light," in Chemical and Physical Behavior of Human Hair, 4th ed., Clarence R. Robbins, Ed. (Springer-Verlag, New York, 2002), pp. 163-171. (2) R. Beyak, G. S. Kass, and C. F. Meyer, Elasticity and tensile properties of human hair. II. Light radiation effects,]. Soc. Cosmet. Chem., 22, 667-678 (1971). (3) R. Arnaud, G. Perbet, A. Deflandre, and G. Lang, ESR study of hair and melanin-keratin mixtures- The effects of temperature and light, Int. J. Cosmet. Sci., 6, 71-83 (1984). (4) E. Hoting, M. Zimmermann, and H. Hocker, Photochemical alterations in human hair. Part II: Analysis of melanins,]. Soc. Cosmet. Chem., 46, 181-190 (1995). (5) H. F. Launer, Effect of light upon wool. Part IV. Bleaching and yellowing by sunlight, Textile. Res.]., 35, 395-400 (1965). (6) A. S. Inglis and F. G. Lennox, Studies in wool yellowing. Part IV. Changes in amino acid composition due to irradiation, Textile. Res.]., 33, 431-435 (1963). (7) W. S. Lee, T. H. Oh, S. H. Chun, S. Y. Jeon, E. Y. Lee, S. Lee, et al, Integral lipid in human hair follicle,]. Invest. Dermatol. Symp. Proc., 10, 234-237 (2005). (8) T. Inoue, M. Ito, and K. Kizawa, Labile proteins accumulated in damaged hair upon permanent waving and bleaching treatments,]. Cosmet. Sci., 53, 337-344 (2002). (9) D. Braida, C. Dubief and G. Lang, Photoageing of hair fiber and photoprotection, Skin Pharmacol., 7, 73-77 (1994). (10) V. Bousquet, D. Black, C. Liviero, J.M. Laquarde, and Y. Gall, Analysis of cuticle relief for hair photoprotection evaluation: Validation study, Curr. Prob. Dermatol., 26, 196-202 (1998). (11) A. Hershko and A. Ciechanover, The ubiquitin system, Annu. Rev. Biochem., 67, 425-479 (1998). (12) A. C. Santos Nogueira, and I. Joekes, Hair color changes and protein damage caused by ultraviolet radiation,]. Photochem. Photobiol. B., 74, 109-117 (2004).